Publisher/Editor: W . D. Cheek, Sr. aka n Dr. Rigoniortis" V1N7: August, 1991
THE WORLD SCANNER REPORT
1 Journal of VHF-UHF Sea nner Technology & Engineering
Published at: COMMtronics Engineering; PO BOX 262478 ; San Diego. CA 92196 Copyright ( c ) 1991 < A 1 1 Rights Reserved) $4.88
SUMMER'S END - RADIO SEASON COMING
Just as Spring is drying in the dusty attic of memory,
summer is now yielding to Autumn. Radio Season will be
upon us once again. Before you know it, the weather will
change and begin to influence a change of our habits.
Picnicking, hiking, swimming, baseball, golf, softball,
bicycle and motorcycle riding will give way to football,
skiing and radioing! This is the time to look at your
antenna & coax cable system and make any needed changes
before the weather turns. You won’t be inclined to
replace your coax in the middle of January. Things to
plan and consider NOW include: new or more antennas, coax
cable changes & upgrades; boosting the height of your
antenna another 10-ft or so; and an annual cleaning &
weatherizing of the antenna & coax. Be sure to at least
give your antennas a good steel-wooling to remove the
season’s accumulation of oxides and corrosion. While
you’re at it, inspect the connectors and the coax cable.
Seal the connectors with a tight wrap of electrical tape
or other moisture-proof covering. Get that outside work
done before the weather turns. I remember a decade or so
ago when I was in the Colorado High Country, how a part
of my Avanti Moonraker 6 antenna worked loose and fell
off in the middle of a January blizzard. Dedicated as we
were, my sons and I lowered the tower and made repairs
while contending with 4-ft snowdrifts and a chill factor
below 0°F. It was a most un-fun experience and one that
I would spare you from if possible. Anything that
disrupts your radioing pleasure in the middle of Winter
is a fate on a par with death and taxes, except that you
can do something about it in advance to keep it from
happening. The other two are etched into stone.
SPEAKING OF ANTENNAS
I’ve said it before and I’ll periodically say it again:
the antenna is the single most important aspect of your
radio station. Depending on your interests in radio; CB,
ham, shortwave, commercial/business or VHF-UHF scanning,
different aspects of the antenna come first and others
last. For instance, to C8’ers, Hams and commercial radio
users, gain of the antenna is of paramount importance.
SWLs and scannists are more concerned with the bandwidth
of the antenna and less with gain.
One unique attribute of all antennas, however, belongs at
the top of the list: HEIGHT! There is no substitute for
height and that’s all there is to it. Starting at HF
freqs around 20 MHz or so all the way up through UHF and
beyond, there can be an effective 3 dB to 6 dB of "gain"
associated with every 10-ft height increment. Raise that
antenna an additional 20’ for a 6-12 dB improvement. In
many cases, raising the antenna can be free or very low
cost. Consider that a low-noise, 12-dB preamp can cost
$100 or more, and will yield less of a performance boost
than a 20’ height increase! Here’s the thing about
antenna height & HF-VHF-UHF radio waves that you need to
know. At about 20-25 MHz & up, radio waves travel pretty
much in straight lines, line of sight, so to speak. A
phenomena called "diffraction” causes all radio waves to
bend slightly beyond the curve of the earth and also into
shadow zones behind obstacles. The amount of bending
varies with frequency, but is not a great amount at best.
Therefore, let’s take for granted the line of sight
aspect of VHF-UHF radio waves. The distance, in miles,
to the horizon from an observer's point of view over
water or "flat" earth is given by:
Dmiles = y/ 2Hft
where Hft = height of view point in feet. As an example,
a person 6’ high at the eyes standing on the beach 2'
above sea level will be able to see no farther than
Dmiles = l/2 (6’ + 2’)
= i/2 x 8’
= 4 miles
Applying this to antennas, the maximum distance in miles
between two antennas that can be in line of sight with
each other is given by the equation:
Dmiles = / 2Haift + \J 2H*2f t
where A1 is the height of the first antenna and A2 is the
height of the second antenna, each in feet. So using the
above example, two antennas, each 8-ft above ground can’t
have a line of sight greater than 8 miles over water or
flat earth. Here are some more solutions to check your
math, or if you don’t want to do the math:
A1 = 50-ft; A2 = 50 ft, then line of sight = 20 mi
A1 = 18-ft; A2 = 32-ft, then line of sight = 14 mi
A1 = 200-ft; A2 = 450-ft, then line of sight = 50 mi
A1 = 5-ft; A2 = 100-ft, then line of sight = 17.3 mi
A1 = 15-ft; A2 = 100-ft, then line of sight = 19.6 mi
The last two examples above can serve as scenarios for
the case of a handheld scanner sitting on a file cabinet
and for another scanner connected to an outdoor antenna
mounted just above the eaves of a house, each of which is
tuned to a local police department’s dispatch freq coming
from an antenna 100-ft high. Note that if your location
is about 17 miles from the tower, then the handheld
scanner will just barely be within line of sight whereas
the outdoor antenna will perform with margin to spare!
Not only does the earth’s curve limit the range of radio
signals because of “shadow effect", but so do hills,
mountains, buildings, dense foliage and other obstacles.
Raw distance between antennas is not nearly the limiting
factor as is the shadow effect from the earth’s curve and
other obstacles. From the above equations, it can be
seen where raising the height of either antenna extends
the maximum line of sight between them. The increase in
line of sight appears undramatic with minor boosts of
antenna height, but something very dramatic happens to a
signal in increments of every few feet due to another
type of signal loss which we’ll call "ground absorption".
Signals in the proximity of the ground weaken at a much
greater rate than the attenuating effect of distance
alone. In fact, absorption is an attenuation factor on a
par with shadow loss in severity. Absorption loss is
greatest on signals closest to the earth but minimizes
markedly with height above ground. Therefore, as an
antenna goes higher, it penetrates into an ever stronger
signal zone as it approaches the window of line of sight.
When LOS is achieved with a distant antenna there is
little else to be gained for THAT signal with further
increases of height. But, the higher an antenna, the
wider its view; therefore the greater its range. Now
let’s put this into perspective.
If you are a casual hobbyist using a rubber duck antenna
or the whip antenna that came with the scanner, then
chances are, depending on your terrain and geography,
your effective range will be not more than 5 to 15 miles.
But with an outdoor antenna a few feet above ground, your
range of hearing can extend out to well beyond 20-miles,
perhaps 30 or so. If you’re a serious hobbyist with an
antenna mounted at 50-ft above ground level, then your
range can easily go to 40 miles and beyond. The thing is
that except for over water or very flat land, earth’s
curve is not so apparent. In fact, certain terrain can
propagate signals far beyond mortal limits. I once lived
at the 6,000-ft level of the Colorado Rockies, and had
line of sight for over 100 miles into portions of NE
Colorado, SW Nebraska, and SW Wyoming. Some rules of
thumb didn’t apply to me, so to speak. But there is one
rule of thumb that applies anywhere and everywhere: the
higher your antenna above ground, the better.
Think of the first 20 to 50 ft above ground as containing
an "RF noise blanket". The limit to ALL radio reception
is NOISE. When a signal approaches the "noise floor" of
a receiver or an area, that’s about it. Hopefully, that
noise floor will be in your receiver and NOT in the area
around you. Unfortunately, most of us live in cities
which are chock full of noise, mostly manmade, which is
the bane of the dedicated SWL, but it’s also serious to
the scannist. Like a smog layer, most urban areas are
smothered with a low level blanket of RF noise which can
limit reception. Within this blanket, VHF & UHF signals
can be fairly strong but difficult to receive because of
competing noise fields. Again, a few extra feet of
antenna height can boost reception by a great margin.
Now just be careful of power lines and falling off the
roof, either of which can kill or maim the unwary.
A MODEST MEMORY UPGRADE FOR THE
PRO-2004/5/6, PRO-32/34; PRO-2021/2022;
BC-760/950XLT: BC-590/600XLT: R-1600
All the above scanners use a 16k static random access
memory (SRAM) chip which can be replaced with a 256k SRAM
for a 16x boost in programmable memory. We can put 6,400
channels in the PRO-2004/5/6 using MOD-16 in my SCANNER
MOD HANDBOOKS . With MODs-19 or 37, we can stick 3,200
channels into the PRO-32/34/2021/2022 and 1,600 channels
in the BC-760/950XLT; BC-590/600XLT and the Regency
R-1600. While hundreds, maybe thousands of these mods
have been done, I continue to hear weird things like,
"Who needs that many channels?", or "Those mods are too
complicated for me!", or "Gee, I don’t want THAT MANY
channels; how about just a few more?" Bruce Heatley of
Buffalo, NY, and I have an ongoing argument about the
relative merits of thousands of channels versus a few
hundred more than stock. Bruce thinks it’s a lot easier
to stick in just a few more channels than the full-blown
methods given in my books. I don’t agree, but since the
controversy persists, despite my professional opinion, I
can do no less than show you how to just double the
number of channels if that’s all you want and need. So,
if you have one of the above scanners, here’s how:
Each of these scanners use a 24-pin surface-mount 2k x 8
SRAM. The chip type number can be any of the following:
TC-5517CF; UPD446G; LC-3517BM or MB-8416. No matter the
number, because they’re all the same. In theory, it’s an
easy matter to double the number of programmable channels
by piggy-backing another chip atop the original one and
paralleling all but one pin of each chip. The difficulty
is soldering 24 hair-thin pins, spaced about a millimeter
apart. To do that, you’ll need a high power magnifier,
preferably the kind worn on your head to leave hands
free. You’ll also need a good soldering pencil with a
very thin tip. Two 100-k resistors, a SPDT switch of
some sort and some fine hookup wire, preferably a bit of
Radio Shack’s #278-776, will be required, as well as the
Service Manual for your scanner.
First locate the memory chip in your scanner, and de-
solder Pin 18. When its solder has melted, gently pry
Pin 18 up from the circuit board with a sewing needle so
that it floats free and does not touch anything. Then
position a new SRAM chip on top of the old one so that
the pins all line up. You might have to bend the pins of
the new chip down so they contact the pins of the stock
chip. Tack solder Pin 12 of the new chip to Pin 12 of
the old chip. Tack solder pin 24 of the new chip to pin
24 of the old chip. These two connections will hold the
chip solidly in place so that you can then tack solder
the remaining pins, pin for pin, except for Pin 18 of
each chip. Do not allow anything to touch Pins 18. These
pins must be isolated from each other and from everything
else. Otherwise, the remaining 21 pins of the new chip
should be soldered to the pins of the stock chip so they
match up, pin for pin. By the way, Pin 18 of this SRAM
chip is known as the Chip Select (CS) or Chip Enable
(CE). The chip is selected for active status when Pin 18
"THE WORLD SCANNER REPORT" (c) 1991; V1N7 - August, 1991; Page 2
is low or 0-volts, and it goes inactive at +5v. Our SPOT
switching scheme will perform that necessary logic.
Refer to Figure 1, the Wiring Diagram, and install the
SPDT switch in a location of choice, but preferably close
to the Logic/CPU area of the scanner . Solder a thin
hookup wire (A) to the now empty PCB pad where Pin 18 of
the stock SRAM chip had been located. Solder the other
end of Wire (A) to the center lug of the SPDT switch.
Prepare two more hookup wires (B) & (C) of about the same
length. Strip X U' from the end of each wire. Tightly
wrap the stripped end of one wire (B) around one lead of
a new 100-k resistor. Push the wrapped hookup wire
tightly up to the body of the resistor and solder in
place. Snip off all but 1 /a " of that end of the resistor
lead. Now prepare the remaining Wire (C) & 100-k
resistor in an identical manner.
FIGURE l: DOUBLE MEMORY WIRING DIAGRAM
AT LAST! ftN S-HETER FOR HOST ALL SCANNERS
Twist together and solder the free ends of the two 100-k
resistors and snip all but about 1 /e" of that dual
resistor lead. Solder a length of thin hookup Wire (D)
to that dual resistor lead. Now solder the resistor end
with wire (B) to the free floating Pin 18 of the stock
SRAM chip. Solder the resistor end with Wire (C) to the
free floating Pin 18 of the new SRAM chip. Solder the
loose end of Wire (B) to one end lug of the SPDT switch.
Solder the loose end of Wire (C) to the other end lug of
the SPDT Switch. Now solder the free end of Wire (D) to
a source of CPU/MEMORY +5v in the scanner. NOTE: This
must be a +5v source that’s never disrupted, regardless
if the scanner is ON or OFF or even disconnected from
power! This is identified for the following scanners:
BC-760/950XLT & R-1600:
CN-504, Pin 2
CN-3, Pin 10
Cathode of D-27
Cathode of D-3
Output of IC-10 at C— 140
Cathode of D-35
Cathode of D-2 or D-3
Unknown at this time
This method of memory expansion doubles the number of
stock programmable memory channels. It’s like having two
identical scanners side by side except that only one at a
time can be used. One position of the switch yields the
stock Block of channels while the other position yields a
second, different Block of the same number. You can flip
between the two Blocks at whim and fancy, any time.
Liabilities are few. The biggest one is that you could
have 8x that many channels for only a little more work
and expense, but maybe this mod is a good one on which to
sharpen your teeth. There could be problems with lengthy
wires between the SRAM chips and the switch which can
pick up noise & spikes, so keep those wires short. If
peculiarities arise in operation, then solder a 0.01-uF
disk cap from each Pin 18 to ground. Also solder a 0.01
cap to ground from the PCB solder pad where stock Pin 18
used to reside. I can supply 2k x 8 SRAMs for US$7.50
ppd, if you can’t find one someuhere else. ED/USR .
Something old; something new. S-meters are about as old
as the hills. S-meters for scanners are fairly new, but
S-meters for just any ol’ scanner are brand new! Eureka!
I made it happen and I’m quite proud of and pleased with
myself (pat pat pat). Now to share the fruits of my labor
FIRST WITH YOU as a way to THANK YOU for your support.
First, a little S-meter theory so you can grip what we’re
about to do. An S-meter provides a visual indication of
the relative strength of incoming signals. An S-meter
operates from a special signal that’s derived from the
incoming signals and which is processed to give about
0-volts on no signal to maybe 1-volt or more on extremely
strong signals. I call it a relative indication, because
looking at an S-meter is just like looking at a scale of
miles on a map. The distance between two cities on a map
might be a couple of inches, but the scale of miles puts
things into perspective. An S-meter does exactly the
same thing. So why don’t all radios come with S-meters?
If it were easy to do, most mfgrs probably would include
an S-meter with their scanners, but the biggest reason
they haven’t is COST. Unlike ham, CB & SW receivers,
scanners don’t have some of the circuitry that makes it
easy to tack on an S-meter. That special circuit is
called AGC or Automatic Gain Control. Scanner’s don’t
require AGC like other receivers because of the unique
characteristics of FM. In the case of FM, there is a
circuit to amplify all incoming signals to the utmost
maximum such that the weakest signals and the strongest
ones all are processed into audio at about the same
strength. Just prior to audio processing, FM signals are
amplified to the hilt and then passed through a ''Limiter"
to strip off noise and hash which is so characteristic of
the CB, ham and SW bands. This is why FM signals are
rarely, if ever, noisy. But it is also why S-meters
can’t work in most scanners. Down at the end of the
receiver string where things count, all signals get
amplified to the same level. The peculiar thing is that
all receivers can benefit from AGC but most manufacturers
don’t design it into scanners. AGC reduces or minimizes
intermod and overload, but it isn’t as essential in the
"THE WORLD SCANNER REPORT" (c) 1991; V1N7 - August, 1991; Page 3
FM-exclusive bands above 30 MHz where scanners work.
Interesting how the PRO-2004/5/6 and only a few other
scanners were designed with AGC and therefore are easily
retrofitted with S-meters. Also interesting that the
PRO-2004/5/6 are virtually immune to overload & intermod!
Well, we can’t yet do anything about the susceptibility
of most scanners to intermod & overload, but we can now
fit them with S-meters at low cost and a little work.
The next step is to understand that part of the scanner
where we will tap a weak signal to be processed by our
new S-meter circuit. For this understanding, you are
referred to V1N4, pp 3-6 of the ’WORLD SCANNER REPORT’,
where NFM chips were discussed. Data sheets are in that
issue for the most common NFM chips in 95% of all
scanners. You don’t necessarily have to have THAT issue,
but it will help you locate and understand your NFM chip
now. We have to avoid needless repetition.
It’s that NFM chip which does so much, working for and
against us. For example, it’s what super -amplifies
signals to maximum gain and makes it tough to put in an
S-Meter. Fortunately, that chip has a pin where we can
access signals before they’re amplified and fed to the
Limiter. NFM chips can include any of the below, although
they’re all pretty much the same except for pin count:
TK— 10420 TK-10421M-2 MC3357 MC3359 MC3361
By now, you should be finding the NFM chip in your
scanner. It will be characterized by the presence of a
455 KHz IF filter at or near Pins 3 & 5. In fact, the
chip’s output to the 455 KHz IF filter will pretty much
always be Pin 3 and the filter will feed the signal back
into Pin 5. There may be exceptions to this, (See Note B
in Figure 4). Now, locate the output of the 455 KHz IF
filter and trace it back to the NFM chip, probably Pin 5.
That’s where we’ll tap the scanner’s weak IF signal and
process it with our add-on circuit for S-Metering. At
this point, the signal has been filtered and cleaned of
adjacent signals and wide band noise, and except for lack
of strength it’s eminently suited for S-metering. The
circuit in Figure 4 does the necessary amplification to
drive either an analog S-Meter or an LED S-Meter, your
choice. For the inside scoop on these two types of
S-Meters, please see MOD-25 and MOD-26 in Vol-2 of my
SCANNER MOD HANDBOOK .
Now examine your scanner for how to do the job. Decide
whether to have an analog S-meter or an LED version;
decide on whether to mount it inside or outside the
scanner. If your scanner is a handheld, relax: you can
put this new mod to work, too. It’s just that everything
will probably have to be put into a metal box external to
the unit. That’s how I developed this mod for my PRO-34,
in which case, nothing had to be done to the scanner
other than to install a Vs" stereo phone jack and wire
one lug to Pin 5 of the NFM chip; another lug to DC POWER
at the VOL control, and the ground lug of the jack to
scanner ground. Except for the 3 connections, this
S-Meter mod is self-contained and independent of the
scanner. The scanner won’t need a radical modification.
So find a source of +8 to +13 volts in your scanner,
usually on the switch part of the Volume Control; find
Pin 5 of the NFM chip, or the pin that gets the signal
from the 455 KHz IF filter; and find scanner ground!
Everything else is independent of the scanner, even if
you choose internal installation.
BUILD THE CIRCUIT on perfboard according to Figures 2, 3
S. 4. Layout is not overly critical, but don’t stray too
far from that shown. Make the board as small as possible
and unless yours is a handheld scanner, the board should
be installed in the scanner as close to the NFM chip’s
Pin 5 as possible, even if your actual S-Meter is going
to be outside the scanner . The reason for this is that
the weak 455 KHz IF signal that has to be tapped for the
board can be a source for noise pickup and needless
radiation to interfere with other things. If a handheld
scanner, well, mount the jack as close to the NFM chip as
possible and use a very short hookup wire from Pin 5 to a
lug of a stereo jack. From the jack on out to the board
and meter, you should use a short length of mini-coax
cable such as RG-177 to carry the 455 KHz signal to the
board. The shield of the coax will be the ground
conductor and a third unshielded wire can be ran along
with the coax for DC power to the board. For base
scanners and external meters, the board should still be
installed inside the scanner as close to the NFM chip as
possible and only two wires need exit the scanner:
ground and S-meter signal. Coax not necessary.
EXPLANATION & ADJUSTMENT OF THE S-METER CIRCUIT
C-l taps a sample of the low-level 455-KHz IF signal into
U-l , a high gain block amplifier. VR-1 sets the desired
gain of U-l. The highly amplified signal goes out of U-l
Pin 8 and is fed to Q-l to amplify the signal a little
more and to isolate the S-meter circuit from U-l. D-l,
D-2, R-6 & C-7 rectify the amplified 455 KHz AC into a DC
signal of proportional strength. That DC signal is then
fed to an analog S-meter for relative indications of
incoming RF signals, or it can be fed to an LED S-meter
for the same results. Depending on the Block gain set by
VR-1, the DC output from D-2 will be about 0-volts when
no signals come in and can be as high as 4 voltst when
exceptionally strong signals are received. VR-1 should
be set so that the DC output from D-2 with no RF signals
coming in is less than 0.2 volts, or so that the S-Meter
reads nearly zero. Then, the scanner should be set to
receive a very strong signal; nearby handitalkies or even
cordless phones can be used for this purpose. VR-2 is
then adjusted so that the S-meter reads at its maximum
point. If an LED S-Meter is used, follow the adjustment
instructions given for MOD-26 in my SMH, Vol-2 .
NOTES FOR LED S-METERS: It might not be possible to get
a pure zero S-reading with this circuit. It’s not a big
deal for analog S-meters which won’t exaggerate slightly
above zero levels. In the case of my LED S-Meter MOD-26,
the first LED might remain ON all the time, even with the
antenna disconnected. There is a solution: modify the
'THE WORLD SCANNER REPORT" (c) 1991; V1N7 - August, 1991; Page 4
LED S-Meter to add a ZERO ADJUST. See VR-3 in the diagram
of M0D-26b on page 119 of my SMH, Vol-2. Add a 10-k trim
pot to M0D-26a with one end lug to ground, the other end
lug to +5v and the middle lug to Pin 4 of the LM-3914
chip. (Don’t ground Pin 4 as shown in the diagram on pg-
109!) Adjust the new trimmer so that the first LED just
goes off with no RF signals coming in. Then simulate a
strong signal with a nearby handitalkie or cordless phone
and adjust the Hi-Cal trimmer so that the 10th LED lites.
NOTE FOR ALL S-METERS. LED OR ANALOG : VR-1 of the Generic
S-Meter Circuit might be very touchy to get set exactly
right, depending on whether the S-meter is analog or an
LED type. Some experimenting may be needed to get it
right. Basically, you want U-l to have plenty of gain
but not so much that the S-Meter can’t read nearly zero
with no signals coming in. Think of VR-1 as a ZERO ADJUST
instead of a gain adjust. VR-2 on either the analog
S-meter or the LED S-Meter board serves as a full-scale
adjustment. So the general idea is to make adjustments
for BOTH zero and maximum signals. In that manner, your
new S-Meter will be calibrated for the extremes of
signals and all others will fall in between.
TABLE l: GENERIC S-METER PARTS LIST
RADIO SHK #
Resistor, 4.7-k 6 .25-watt
Resistor, 1-k § .25-watt
Resistor, 330-ohm @ .25-watt
Resistor, 1-Meg § .25-watt
Resistor, 1-k @ .25-watt
Resistor, 2.2-k § .25-watt
Resistor, 47-k § .25-watt
Resistor, 10-k @ .25-watt
Resistor, 2.2-k § . 25-watt
Diode, germanium; 1N34A
Variable resistor, trimmer, 10-k
IC; MC-1350P or ECG/NTE-746 non-
JFET , N-channel, MPF-102
Hookup wire, solder, mounting hdwe
Optional, depending on need
Variable resistor, trimmer, 10-k
Analog S-meter; salvaged from old CB
radio or purchased from repair parts
department of various radio mfgrs.
See MOD-25 in SMH, Vol-1
Mid LED S-meter; see MOD-26, SMH, Vol-2
Misc Jacks or connectors to connect external Various
S-meter to scanner; stereo phone jack
required for handheld scanners.
1 R-2 should be 1.3-k, but R/S doesn’t carry it.
2 R-6 should be 56-k, but R/S doesn’t carry it.
3 U-l can also be an MC-1590G, but the pinout
differs from the MC-1350. See Figure 4.
FIGURE 3: GENERIC S-METER BOARD WIRING SIDE
GENERIC S-METER CONCLUSION & SUMMARY: This S-meter is
not limited to scanners! It is adaptable to any kind of
radio: CB, ham, shortwave, AM/FM, 49 MHz handheld, land-
mobile, satellite, etc. The MC-1350P chip is good for-RF
up to 50-90 MHz, so there could be other uses for this
circuit besides S-meter ing! The chip is versatile and so
is the circuit. Use your imagination!
YOU readers of the ’USR" are the first to learn of this
important new modification. The Generic S-Meter is in
its first stage of design and prototype evaluation.
While I didn’t run into any bugs or unusual difficulties
developing it on a PRO-34, certain peculiarities could
arise in other radios. I want your feedback and notes of
problems & improvements. My guess is that this circuit
can be improved, but as given here, it works great.
It’s impossible for me to give out specific installation
instructions for specific scanners and other radios. But
if you run into trouble with this project, AND if you
have the Service Manual for the radio, I am available to
render written assistance to steer you back on the narrow
and righteous path to success. All I ask is that you
include with your request a SASE, one loose extra stamp
and a copy of the Service Manual, if I don’t have one.
PRO-2004/5/6 OWNERS, PLEASE NOTE that this circuit is not
for your scanner! Aw, it would work ok, but why do it
when my MODs 25 & 26 are tried, proven and easier? In
other words, there’s not much sense in doing this S-meter
on the PRO-2004/5/6 because I’ve already developed great
S-meters for them. The Generic S-Meter is for all other
scanners & radios for which an S-Meter circuit has not
been concocted. But if you feel like playing, the
circuit given here will work for the PRO-2004/5/6, too.
"THE WORLD SCANNER REPORT" (c) 1991; V1N7 - August, 1991; Page 5
FROM THE READERS.
* X M X
TERRY HftRN ON THE ICOM R-l
From John Morris; UA: I read in the Feb issue of the
’WORLD SCANNER REPORT’ about 'low noise, wideband
preamps" built by Japan Information Medium. Interesting.
Particularly your mention, on p-3, 2nd column, under JIM
M-75, last sentence, '..really works, often dramatically,
providing signals with full quieting from well beyond 100
miles . “ It just dawned on me that you don’t mention the
antennal s) used during your evaluation of the M-75.
Well, as you can probably guess, I’m kinda curious about
an antenna system that, with a preamp attached, can pick
up signals well beyond 100 miles. What is it? /JM
EDITOR ’S REPLY: I should have mentioned the antenna used
in testing the preamps, but it was an insignificant
oversight. It’s a discone of Japanese origin, an Araki
YA-DC, but not distributed in the USA. It’s similar to
the ICON AH-7000 and the Diamond D-130J. Discones are
omnidirectional and extremely widebanded. Consequently,
it has no gain, maybe less than 0 dB. So, the antenna
was not a special factor in evaluating the preamps. I am
north of San Diego on a mesa about 480-ft above sea
level. We are not in line of sight of Los Angeles
(140-mi), but the land path is maybe 15-mi before
encountering sea path the rest of the way. I routinely
pick up LA’s VHF/UHF public service repeaters. The
preamps dig in and catch some of the ground units and
lots of cell sites, trunk sites and even low powered
mobiles. My location may be a special factor but even
so, the preamp still digs things out of the noise with
full quieting that can’t be heard at all without it. I
also pick up nice clean 1296 MHz signals with the preamps
that can’t be detected even with the squelch turned down!
Another special factor is that I use high quality, low
loss coaxial cable. This alone can make a difference!
Nice to hear from you, John! 73/BC
From Larry McDermott. CA: I understand that ACE
Communications is dropping their AR-2500 and coming out
with a new model very soon called the AR-2800. It is
supposed to be free of the many bugs in the 2500. It is
to have much better side band reception. I hear they are
dropping the built-in RS-232 port to keep the price down.
Maybe you can find out more about this new unit and
report on it in one of your articles. My AR-950S work
fine. Maybe it is just as well that I waited a while
before buying an AR-2500. Thank you/LM
EDITOR 'S REPLY: j haven’t heard about an AR-2800. ACE
ignores me like the plague, it seems. I have sent them
numerous inquiries, requests for information, etc, but
rarely a reply and never a personal one. I wonder if
it’s because I tend to tell it like it is and maybe they
are afraid of what I might have to tell? I dunno — I
have heard something about a new ACE GaAsFET, low-noise
wideband preamp that will actually work! I’d say their
scanners have room for improvement and if that’s what
they’re doing, more power to them! I’m with you that some
things are worth the wait. 73/BC
I’d like to share with your readers the discovery I made
recently about a hot new scanner, the ICOM R-l. Imagine
if you will, a receiver that covers 100 KHz - 1300 MHz
with no gaps. There are 10 Search Banks and 100 Memory
Channels. The R-l SEARCHes in steps of .5,5,8,10,12.5,
15,20,25,30 & 50 KHz. At the press of a button it can
also jump in steps of .1, 1, 10 or 100 MHz. Yes, MHz!
The R-l covers AM, NFM and WFM modes, selectable at the
touch of a button. There is a manual tuning knob used in
SEARCH and SCAN and in selecting its many features:
+ LCD signal strength meter.
+ RX light; can be de-activated if desired.
+ Volume controlled confirmation beeps; de-selectable.
+ Monitor button to momentarily remove the squelch.
+ LCD Display Contrast control for better angle viewing.
+ 24-hour clock w/sleep timers in 20, 40 or 60 min
+ Wake Up Alarm; 5 beeps, then plays last active freq
+ Back lit display; on-off button, or auto off after
5-sec from last keyboard entry.
+ Speeds of 10 or 20 channels per second.
+ 2 Freq Lockouts; skip or mask;, mask hides the memory
freq from all scanning methods, skip is not so harsh.
+ 3 Scans: Select Scan scans high/low limits except
"skips"; Program Scan scans all freqs in memory;
Mode Scan scans by mode (AM, FM or WFM).
+ Scan Limit; selectable for High / Low limits.
+ Search & Store memory feature.
+ Search Freq Skip; no lock up on known birdies, etc.
The ICOM R-l fits in a shirt pocket, and weighs 9.9 oz
including the built in rechargeable batteries. Input
voltage is very flexible, accepting from 6 to 16 volts DC
with 13. 8v required for recharge. External batteries that
clip on other ICOM handhelds just snap on the R-l, too.
Sensitivity is good, although LF & MF can be tough to get
especially 560 - 1600 KHz, but a different antenna than
the one supplied from the factory helps a lot. I use a
telescoping whip from Radio Shack. The R-l has a BNC
connector, so changing antennas is a snap, literally.
Audio is excellent considering size. In fact all of the
R-l is surprising for the size. Imagine going from a
talk show on 710 AM to Radio Havana to police, fire and
ambulance to music FM to TV Ch-4 News to cordless and
cellular phones to boats to taxi cabs to military traffic
in minutes with one radio that can be hidden under your
hat. Imagine the applications for "Surviva-Comm"; its
flexible power requirements making it ideal. Too bad you
can’t buy the ICOM R-l in the United States. /Terry Harn
EDITORS REPLY : At first, I wasn’t going to run your
review because the R-l isn’t available in the USA. But
then I got to thinking why not? None of us know why
the R-l isn’t available, and apparently ICOM won’t say.
Perhaps ICOM will say something in the media if enough
readers and Hobbyists ask about the R-l . 73/bc
"THE WORLD SCANNER REPORT" (c) 1991; V1N7 - August, 1991; Page 6
FIGURE 4: GENERIC S-METER SCHEMATIC/WIRING DIAGRAM
"THE WORLD SCANNER REPORT" (c) 1991; V1N7 - August, 1991; Page 7
CONFIDENTIAL SUBSCRIPTION ORDER:
Please print clearly
PHONE :( )
THE BELOU OOFS HOWS ARE OPTIONAL BUT UILL HELP US HELP YOU!
Radio Interests? (Put YEARS OF EXPERIENCE in each block that applies)
VHF-UHF Amateur CB Shortwave Professional
Scanning? Radio? Radio? Listening? Radio?
List makes & models of your scanners & other radio equipment:
07/24/91 SUBSCRIPTION RATES t ORDER BLANK V1N7
USA RATES: (Canada +10*; Other Foreign +20*-surf or +40*-Air)
BACK ISSUES OF THE HSR Check Items
1991 Single copies; your choice: i ea $ 4.00
1991 (1st 6-mos, Jan-June) 5 ea $15.00
CURRENT SUBSCRIPTIONS, with and without Back Issues (BI)
1991 (2nd 6-mos; Jul-Oec, w/o BI) 5 ea $15.00
1991 (1-yr; Jan-Dec, w/BI) 10 ea $25.00
1991-92 (1-yr; Jul-Jun, w/o BI) 10 ea $25.00
1991-92 (1.5-yr, Jan-Jun w/BI) 15 ea $35.00
1991-93 (2-yr Jul-Jun, w/o BI ) 20 ea $45.00
1991-93 (2.5-yr, Jan-Jun w/BI) 25 ea $52.50
OTHER LITERATURE AVAILABLE
SCANNER MOO HNOBK, Vol-1 : $17.95 t $3.00 SJH *
SCANNER MOO HNOBK, Vol-2: $17.95 + $3.00 S&H *
XCanada $4 S&H; Other Foreign $5 S&H; add extra for Air Mail)
HOBBY RADIO BUYER’S DIRECTORY (600+ listings) $14.95 ppd
Describe your technical abilities & interests; use reverse as needed.
HAKE REMITTANCE PAYABLE IN US FUNDS TQ: COHHTRONICS ENGINEERING
Enclose a #10 S.A.S.E. and one loose extra stamp if you want
hobby info i personal reply! Business inquiries exempt.
ERROR CORRECTIONS TO THE SCANNER MODIFICATION HANDBOOK WRAPPING IT UP FOR THIS MONTH
More funky little errors have turned up. Grab your pen
and make changes in your copy of Vol-2 as follows:
MOO-5: First change is to an error reported in USR V1N5,
page 1: I made an error in reporting the error, dang it!
Referring to page 83, MOD-5, Step B, "Pin 6 of IC-6"
should be changed to read, * Pin 3 of IC-6". Step C is
correct as written and VlN5pl is wrong as reported.
MOD-28: On p-142 of Vol-2, the photo caption errs in item
C, which should read "MOD-16" instead of "M0D-26“. Now
and again, I run into a little trouble with the Power On
Auto Reset function of MOD-28, the KeyBoard Memory Block
Controller. When you turn the scanner ON, the Home Block
00 should be selected. Sometimes other Blocks are
selected. A sure cure for this is to change C-2 on pages
140-141 from a 0.1-uF capacitor to a 2.2-uF capacitor ,
MOD-29: The photo captions on pp 160-161 are both in
error. “EMB" should be changed to read, "EDB " .
MOD-40: Page 206, has an error in Step 4. Change "4.7-k
resistor” to read "10-k resistor * . While you’re at it,
add "R-215" by where it says, "leadless resistor". Then,
add to the end of the sentence in Step 3, "where R-215
connects to Pin 40 of the CPU1 - Then, back to Step 4,
add just after "K-1013", (IC-296. Pin 8} .
MOD-43: Next, turn to page 79 of Vol-2 and see the
photo, Label C, reported as MOD-43. You won’t find
MOD-43 in the book because the Publisher wouldn’t print
it, but the photo correctly shows the position of the SCA
Board, MOD-43. Some people hunted through the book,
inside and out looking for MOD-43. It ain’t there, but
see V1N1 of the WSR for all pertinent details.
Apologies for any inconvenience caused by these goofs.
Dang, I just hate it when there a short column left; not
enough space to get into anything too deep, and too much
space to fill with one-liners. Ok, how about a preview
of things to come?
MORE MEMORY? Some folks think that 1,600 to 6,400
channels as given by my MODs 16/19/37 to various scanners
is just too many channels. How can this be? Memory is
one of those deals where if a little bit is good, then a
whole bunch is better. Coming soon, if all goes well,
will be a method to give your PRO-2004/5/6 exactly 25,600
channels, organized into 64 Blocks of 400-channels each.
The PRO-2021/2022/32/34 can get 12,800 channels in 64
Blocks of 200-channels each. The BC-760/950/590/600XLT
and the Regency R-1600 can get 6,400 channels in 64
Blocks of 100-channels each. There’s no secret to this
mod; just use a 1-megabit SRAM instead of a 256k as we
have been doing. A few more wires, two extra switches or
a little more wiring on the KMBC MOD-28 is all that’s
required to go for the gusto! The 1-meg SRAM costs an
arm and a leg, but less than four 256-k SRAMS which is
another way this mod could be done. The greatest value
of this huge memory expansion technique is not so much
the number of channels; rather, the number of Blocks,
which permit different configurations & scanning programs
so that you can have more choices of what to scan and
search for on any occasion.
COMPUTER INTERFACING? Imagine punching in a few thousand
freqs by hand! I’ve done it, but it ain’t much fun.
We’re still working on an RS-232 interface that can be
used by most any computer with a serial port. Lots of
problems yet to overcome, but we’re making progress. The
problems have more to do with making one universal design
for ASCII transfers than making a given computer program
the scanner. We’ve done that much, but an Apple-specific
circuit won’t help most of you. Sure could use some hard-
ware design help if anyone’s capable. 73/bc
"THE WORLD SCANNER REPORT" (c) 1991; V1N7 - August, 1991; Page 8
"THE WORLD SCANNER REPORT
PO BOX 262478
SAN DIEGO, CA 92196-2478
THl LATEST COSSIP IS
that the replacement for the PRO-34 *111 be the PRO-37.
Some say it is already being sold i o Canada, and it is said
to be identical to the PRO-34 except for slightly faster
SCAB i SEARCH speeds. Supposedly, it loots like the PRO-34,
feels like the PRO-34, acts like the PRO-34, but is a PRO-37
uith a price considerably less than the PRO-34. The PRO-34
have been on sale several times this last year so apparently
ne've seen the last of it. Radio Shack's neu 1992 Catalog
xill tell all, and Kill be available sometime this month.
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